I love navigator, i used it in a long trip and the offline maps are very accurate, the app can even calculate the fastest route to a location while providing turn by turn voice guidance completely offline, all that with an amazing level of accuracy, definitely a must buy if you own a wifi playbook.
The dev just released a version of this app thats works online for just 0.99! Just search in the app world navigator and if you have any questions about this app I can answer them.